KR102188566B1 - Superconducting wire material substrate, production method therefor, and superconducting wire material - Google Patents

Abstract

An object of the present invention is to provide a substrate for a superconducting wire for manufacturing a superconducting wire having excellent superconducting properties and a method of manufacturing the same. Superconductivity in which the crystal orientation of the metal of the outermost layer is 99% or more in the c-axis orientation rate, ΔΦ is 6° or less, and the ratio of the area whose crystal orientation deviates by 6° or more from (001)[100] is 6% or less per unit area. Substrate for wire rod.

Description

Superconducting wire material substrate, production method therefor, and superconducting wire material}

The present invention relates to a substrate for a superconducting wire and a method of manufacturing the same. Further, it relates to a superconducting wire material using a substrate for a superconducting wire material.

Superconducting wire is laminated on a metal substrate or an intermediate layer made of an oxide layer such as single or multiple layers of cerium oxide (CeO ₂ ), zirconia-added yttrium oxide (YSZ), and yttrium oxide (Y ₂ O ₃ ). It is manufactured by laminating a superconducting layer (RE123 film, RE: Y, Gd, Ho, etc.) on one base material.

As a technology for obtaining a crystal-oriented superconducting layer, the ion assisted beam film formation method (IBAD method) in which the crystal orientation is inherited to the superconducting layer by forming an oriented intermediate layer on an unoriented metal substrate such as Hastelloy, or a biaxial crystal oriented A method of forming a film by inheriting an intermediate layer, a superconducting layer, and a crystal orientation by using a metal substrate (RABiTS method, etc.) is known. The latter method is advantageous when future production efficiency such as film formation speed is considered, but it is necessary to highly biaxially crystalline the metal substrate to improve superconducting properties. Here, the crystal orientation of the metal substrate is evaluated according to, for example, the c-axis orientation rate of the outermost layer of the substrate or the value of ΔΦ.

As such a metal substrate (substrate for a superconducting wire), a substrate in which crystal-oriented copper is laminated on a stainless steel substrate and nickel is further laminated thereon is known. For example, Patent Document 1 includes a metal layer and a copper layer bonded to at least one side of the metal layer, and the copper layer has an epitaxial structure having a {100}<001> cubic structure in which ΔΦ is ΔΦ≦6°. A clad-oriented metal substrate for thin film formation is disclosed.

In addition, in Patent Document 2, a non-magnetic metal plate and a metal foil made of Cu or Cu alloy cold-rolled at a high pressure reduction rate are laminated by surface activation bonding, and the metal foil is biaxially oriented by heat treatment after lamination, and then the metal foil side A method of manufacturing a metal substrate for a superconducting wire is disclosed that imparts an epitaxial growth film of Ni or Ni alloy to the surface, and the metal substrate obtained by this method is described that the crystal orientation rate or ΔΦ of the Ni plating layer of the outermost layer is improved. have.

In addition, Patent Document 3 discloses a process of sputter etching the surface of a copper foil to remove the adsorbed material on the surface, a process of sputtering the surface of a nonmagnetic metal plate to remove the adsorbed material on the surface, and the copper foil and the metal plate. A step of bonding with a pressure of 300 MPa to 1500 MPa with a rolling roll, a step of crystal-aligning the copper by heating the bonded laminate to a temperature equal to or higher than the crystal orientation temperature of copper, and protection on the copper side surface of the laminate A method for manufacturing a metal substrate for a superconducting wire, characterized in that it has a step of coating a layer, is described, and the metal substrate obtained by this method is described that the c-axis orientation rate and ΔΦ of the copper foil and Ni plating layer are improved. .

Patent Document 1: Japanese Laid-Open Patent No. 2008-266686 Patent Document 2: Japanese Laid-Open Patent Publication No. 2010-118246 Patent Document 3: International Publication No. 2011/007527

As described above, conventional substrates for superconducting wires are manufactured by setting the c-axis orientation rate or the value of ΔΦ of the outermost layer of the biaxially crystal-oriented metal substrate as a specific value, and the higher the c-axis orientation rate, the more ΔΦ is It is known that the smaller the size is, the better the superconducting wire can be obtained.

However, in the conventional superconducting wire, even when a metal substrate having a c-axis orientation rate and ΔΦ having sufficient crystal orientation of the metal of the outermost layer is used, the superconducting properties of the superconducting wire obtained using this substrate may be uneven.

Therefore, an object of the present invention is to provide a substrate for a superconducting wire for manufacturing a superconducting wire having excellent superconducting properties, and a method of manufacturing the same.

As a result of scrutinizing the present inventors in order to solve the above problems, the crystal orientation of the metal in the outermost layer of the substrate for a superconducting wire has a specific c-axis orientation rate and ΔΦ, and the crystal orientation of the outermost layer is (001)[ 100], by controlling the ratio of the area deviating from a specific angle or more within a predetermined range, it was found that it was possible to obtain a superconducting wire with improved superconducting properties, and the invention was completed. That is, the gist of the present invention is as follows.

(1) The ratio of the area in which the crystal orientation of the metal of the outermost layer is at least 99% c-axis orientation, ΔΦ is 6° or less, and the crystal orientation deviates by 6° or more from (001)[100] is the unit area ( Substrate for superconducting wire with less than 6% per 1㎟).

(2) The substrate for a superconducting wire according to (1), wherein the outermost layer is made of copper, nickel, or an alloy thereof.

(3) A method for producing a substrate for a superconducting wire according to (1) or (2), wherein the c-axis orientation ratio is 99% or more by heat treatment, ΔΦ is 6° or less, and the crystal orientation is (001)[100 ] The manufacturing method comprising the step of forming a layer in which the ratio of the area deviating from 6° or more is 6% or less per unit area.

(4) The process of laminating the non-magnetic metal plate and the high-pressure rolled metal layer by surface activation bonding, and the c-axis orientation rate is 99% or more, ΔΦ is 6° or less, and the crystal orientation is 6° at (001)[100]. A method of manufacturing a substrate for a superconducting wire comprising a step of performing a heat treatment of a high-pressure rolled metal layer so that the ratio of the area deviated from the above is 6% or less per unit area.

(5) The production method according to (4), wherein the glossiness of the high-pressure rolled metal layer before lamination is 45 or less.

(6) A superconducting wire comprising the substrate for a superconducting wire according to (1) or (2), an intermediate layer stacked on the substrate, and a superconducting layer stacked on the intermediate layer.

This specification includes the contents described in the specification and/or drawings of Japanese Patent Application No. 2013-183031 which is the basis of the priority of the present application.

According to the present invention, with respect to the crystal orientation of the metal of the outermost layer of the substrate for a superconducting wire, the c-axis orientation rate is specified to be 99% or more, and ΔΦ is 6° or less, and further, the crystal orientation is 6° or more in (001)[100]. By specifying the ratio of the deviated area to 6% or less per unit area, a substrate for manufacturing a superconducting wire having excellent superconducting properties can be obtained.

1 is a diagram showing EBSD measurement results of a substrate of Example 2. FIG.
2 is a diagram showing the EBSD measurement results of the substrate of Comparative Example 1. FIG.
3 is a diagram showing superconducting properties of the superconducting wires of Example 4 and Comparative Example 3;

Hereinafter, the present invention will be described in detail.

1. Superconducting wire substrate

In the substrate for a superconducting wire of the present invention, the crystal orientation of the metal of the outermost layer is 99% or more, the ΔΦ (in-plane orientation) is 6° or less, and the crystal orientation is 6° or more at (001)[100]. It is characterized in that the ratio of the deviated area is less than 6% per unit area (1 ㎟). Here, ΔΦ represents the degree of in-plane orientation. ΔΦ is an average value, and it is not known how far each crystal grain deviates, so it is not an index of the area ratio where the crystal orientation deviates from (001)[100] by more than a specific angle.

In the present invention, "the ratio of the area in which the crystal orientation deviates from (001)[100] by more than ○○°" is a crystal area in which the angle difference from (001)[100] is greater than or equal to ○○° when observed by the EBSD method Says the ratio of. Here, EBSD (Electron Back Scatter Diffraction) means a crystal orientation using reflected electron Kikuchi ray diffraction (Kikuchi pattern) that occurs when an electron beam is irradiated to a sample in a SEM (Scanning Electron Microscope). It is a technique to interpret. Usually, an electron beam is irradiated to the surface of the outermost layer, and the information obtained at this time is orientation information up to a depth of several 10 nm through which the electron beam penetrates, that is, orientation information of the outermost layer.

The substrate for a superconducting wire of the present invention is characterized in that the ratio of the area in which the crystal orientation of the metal of the outermost layer deviates from (001)[100] by 6° or more is 6% or less per unit area. By setting the crystal orientation of the metal of the outermost layer of the substrate in this manner, the superconducting properties of the superconducting wire obtained using this substrate can be improved.

In the substrate for a superconducting wire of the present invention, preferably, the ratio of the area in which the crystal orientation of the metal of the outermost layer deviates by 10° or more from (001)[100] is less than 1% per unit area, and the area deviates by 15° or more The ratio of is less than 0.3% per unit area. In the superconducting wire obtained by doing in this way, very excellent superconducting properties can be achieved.

It is preferable that the outermost layer of the substrate for a superconducting wire of the present invention is a face-centered cubic lattice metal, for example, one or more selected from the group consisting of nickel, copper, silver, aluminum, and palladium, or an alloy thereof, and 2 It is preferably made of copper, nickel or an alloy thereof from the viewpoint of easy axial crystal orientation and good lattice matching with the intermediate layer.

In the substrate for a superconducting wire of the present invention, the outermost layer only needs to have the crystal orientation and crystal orientation of the metal, and there may be another non-oriented metal layer in the lower layer thereof.

The thickness of the substrate for a superconducting wire of the present invention is not particularly limited, but is preferably 50 µm to 200 µm. This is because if the thickness is less than 50 µm, the mechanical strength of the substrate cannot be secured, and if the thickness is greater than 200 µm, the workability at the time of processing the superconducting wire cannot be secured.

In one embodiment of the present invention, the substrate for a superconducting wire of the present invention includes a non-magnetic metal plate and a crystal-oriented high-pressure rolled metal layer (hereinafter also referred to as a crystal-oriented metal layer) laminated on the non-magnetic metal plate. Further, a high-pressure rolled metal layer Crystal-oriented by heat-treating (referred to as a crystal-oriented metal layer). Further, the high-pressure rolled metal layer may be laminated on only one side of the nonmagnetic metal plate, or may be laminated on both sides of the metal plate.

In the present invention, "non-magnetic" refers to a state in which a non-ferromagnetic material is not ferromagnetic at 77 K or higher, that is, a Curie point or Nell point exists at 77 K or less, and becomes a paramagnetic or antiferromagnetic material at a temperature of 77 K or higher. As the non-magnetic metal plate, a nickel alloy or austenitic stainless steel plate is preferably used from the viewpoint of having a role as a reinforcing material excellent in strength.

In general, austenitic stainless steel is in a non-magnetic state at room temperature, that is, the metal structure is 100% austenite (γ) phase, but when the ferromagnetic martensite (α') phase transformation point (Ms point) is located at 77K or higher, There is a possibility that the α'phase, which is a ferromagnetic substance, may be expressed at liquid nitrogen temperature. Therefore, as a substrate for a superconducting wire used under a liquid nitrogen temperature (77K), a substrate having an Ms point of 77K or less is preferably used.

As the γ-based stainless steel sheet to be used, a sheet material such as SUS316 or SUS316L, SUS310 or SUS305 is preferably used in that it has a stable γ phase designed to have an Ms point sufficiently lower than 77K, and is generally popular and can be obtained at relatively low cost. The thickness of these metal plates is usually applicable as long as it is 20 µm or more, and is preferably 50 µm to 100 µm in consideration of the thinning (thickness in thickness) and strength of the superconducting wire, but is not limited to this range.

In the present invention, the term ``high-rolled metal layer'' is cold-rolled at a high-pressure reduction ratio of preferably 90% or more, more preferably 95% or more at the final rolling, and heat treatment for recrystallization is not performed after the cold rolling. It does not mean a metal layer having a rolling texture developed by cold rolling. If the reduction ratio is less than 90%, there is a fear that the metal may not be oriented in the heat treatment performed later.

The high-pressure rolled metal layer used for the substrate of the present invention may be selected from metals that are crystal-oriented by performing heat treatment after rolling, for example, one or more selected from the group consisting of nickel, copper, silver, and aluminum, or alloys thereof, It is preferably made of copper or a copper alloy from the viewpoint of easy biaxial crystal orientation and good lattice matching with the intermediate layer.

The high-pressure rolled metal layer may contain a trace element of about 1% or less in order to further improve the biaxial crystal orientation by the later heat treatment. Examples of such additional elements include at least one element selected from Ag, Sn, Zn, Zr, O, and N. These additive elements and the metal contained in the high-pressure rolled metal layer form a solid solution, but when the amount exceeds 1%, impurities such as oxides other than the solid solution increase, which may adversely affect the crystal orientation.

Metal foil is preferably used as the high-pressure rolled metal layer. Metal foils that can be used are generally available. For example, JX Nikko Nisseki Metals Co., Ltd. high-pressure rolled copper foil (HA foil (brand name)) or Hitachi Electric Wire Co., Ltd. high-pressure rolled copper Park (HX foil (brand name)) and the like.

The thickness of the high-pressure rolled metal layer is preferably in the range of 7 µm to 70 µm in order to ensure the strength of the high-pressure rolled metal layer itself and improve workability when processing the superconducting wire later.

In the substrate for a superconducting wire of the present invention, as one method for making the ratio of the area in which the crystal orientation of the metal of the outermost layer of the substrate deviates by 6° or more from (001)[100] to 6% or less per unit area, gloss A high-pressure rolled metal layer such as copper foil having a degree of 45 or less, preferably in the range of 20 to 45, and more preferably in the range of 20 to 43 can be used. Here, the glossiness is an L value obtained by measuring L*, a*, and b* with a color difference meter for a high-pressure rolled metal layer after lamination on a non-magnetic metal plate and after rolling in a method for producing a substrate described later.

Further, the substrate for a superconducting wire of the present invention may include a protective layer formed on the crystal oriented metal layer.

The protective layer used in the substrate for a superconducting wire of the present invention is preferably a face-centered cubic lattice metal, for example, nickel, palladium, silver, or an alloy thereof, and preferably nickel or a nickel alloy. The protective layer containing nickel has excellent oxidation resistance, and the presence of the protective layer prevents the formation of an oxide film of the metal contained in the crystal orientation metal layer when forming an intermediate layer such as CeO ₂ thereon, thereby preventing the crystal orientation from being destroyed. Because there is. As an element contained in an alloy of nickel, palladium, or silver, it is preferable that the magnetic property is reduced, and examples thereof include elements such as Cu, Sn, W, and Cr. In addition, impurities may be contained in a range that does not adversely affect the crystal orientation.

If the thickness of the protective layer is too thin, when the intermediate layer and the superconducting layer are laminated thereon in the manufacture of a superconducting wire, there is a possibility that the metal in the crystal-oriented metal layer diffuses to the surface of the protective layer, causing the surface to be oxidized. It is appropriately set in consideration of these points because the crystal orientation is broken and the plating deformation also increases. Specifically, it is preferably in the range of 1 µm to 5 µm.

2. Method of manufacturing a substrate for superconducting wire

The substrate for a superconducting wire of the present invention has a c-axis orientation rate of 99% or more by heat treatment, a ΔΦ of 6° or less, and the ratio of the area in which the crystal orientation deviates from (001)[100] by 6° or more per unit area. It can be manufactured by a method including a step of forming a layer of 6% or less.

In one embodiment of the present invention, the c-axis orientation rate formed by heat treatment is 99% or more, ΔΦ is 6° or less, and the crystal orientation is at least 6° from (001)[100]. The layer with a ratio of 6% or less per unit area is a crystal-oriented metal layer.

The heat treatment is performed at, for example, 150°C or higher. The heat treatment time varies depending on the temperature, but for example, 400°C for 1 to 10 hours, and 700°C or higher for several seconds to 5 minutes. If the heat treatment temperature is too high, the high-pressure rolled metal layer is liable to cause secondary recrystallization and the crystal orientation deteriorates, so the temperature is 150°C or more and 1000°C or less. In the later process of forming the intermediate layer or the superconducting layer, heat treatment at 600° C. to 900° C. is preferable when the substrate is placed in a high temperature atmosphere of 600° C. to 900° C. More preferably, the crystalline orientation and surface roughness of the crystal oriented metal layer and the protective layer formed thereafter are improved by performing the heat treatment at a high temperature after heat treatment at a low temperature step by step. Specifically, it is particularly preferable to perform heat treatment at 800 to 900°C after heat treatment at 200 to 400°C.

In one embodiment of the present invention, the substrate for a superconducting wire includes a step of laminating a non-magnetic metal plate and a high-pressure rolled metal layer by surface activation bonding, a c-axis orientation rate of 99% or more, ΔΦ is 6° or less, and It is manufactured by a method including a step of performing heat treatment of the high-pressure rolled metal layer so that the ratio of the area whose crystal orientation deviates from (001)[100] by 6° or more is 6% or less per unit area.

In the method of manufacturing a substrate for a superconducting wire of the present invention, in order to set the ratio of the area in which the crystal orientation of the outermost layer of the substrate for a superconducting wire to be obtained is 6° or more from (001)[100] to be 6% or less per unit area, For example, a method of adjusting the glossiness of a high-pressure rolled metal layer such as a copper foil to be used is mentioned. The glossiness of the high-pressure rolled metal layer is, for example, 45 or less, preferably in the range of 20 to 45, and more preferably in the range of 20 to 43. Here, the glossiness is an L value obtained by measuring L*, a*, and b* with a color difference meter for a high-pressure rolled metal layer after rolling before being laminated on a nonmagnetic substrate. In addition, other than the method of adjusting the glossiness of the high-pressure rolled metal layer is not particularly limited, for example, the ratio of the copper orientation (Copper orientation) in the rolled aggregate structure of the high-pressure rolled metal layer is increased and the ratio of the brass orientation (Brass orientation). By lowering, the ratio of the area in which the crystal orientation of the outermost layer of the substrate after heat treatment deviates by 6° or more from (001)[100] can be set to 6% or less per unit area.

In the method of manufacturing a substrate for a superconducting wire of the present invention, the process of laminating a non-magnetic metal plate and a high-pressure rolled metal layer by surface activation bonding. In the surface activation bonding, sputter etching treatment is performed on the surfaces of each of the non-magnetic metal plate and the high-pressure rolled metal layer The surface adsorption layer and the surface oxide film are removed and activated, and then the two activated surfaces are joined by cold pressing.

In the surface activation bonding, specifically, a non-magnetic metal plate and a high-pressure rolled metal layer are prepared as a long coil having a width of 150 mm to 600 mm, and two surfaces to be bonded are pre-activated, followed by cold pressing.

In the surface activation treatment, a non-magnetic metal plate having a bonded surface and a high-pressure rolled metal layer are grounded as one electrode, respectively, and a glow discharge is generated by applying an alternating current of 1 MHz to 50 MHz between the other insulated and supported electrodes. The area of the electrode exposed in the plasma generated by the glow discharge is performed by sputtering etching in 1/3 or less of the area of the other electrode. As the inert gas, argon, neon, xenon, krypton, or the like, or a mixed gas containing at least one of them can be used.

In the sputter etching treatment, at least the surface adsorption layer may be removed by sputtering the surface to which the non-magnetic metal plate and the high-pressure rolled metal layer are joined with an inert gas, and further, the surface oxide film may be removed, and the surface to be joined is activated by this treatment. During this sputter etching treatment, the earth-grounded electrode takes the form of a cooling roll, preventing temperature rise of each conveying material.

After that, it is continuously conveyed by a pressure welding roll process, and activated faces are pressure-welded. In the atmosphere under pressure bonding, if O ₂ gas or the like is present, the activated surface is re-oxidized during transport and affects the adhesion. The laminated body brought into close contact through the pressure welding process is conveyed to the winding process and is wound here.

Further, in the sputter etching step, the adsorbed material on the bonding surface is completely removed, but the surface oxide layer does not need to be completely removed. This is because even if the oxide layer remains on the entire surface, the bonding property between the non-magnetic metal plate and the high-pressure rolled metal layer can be secured by increasing the reduction ratio in the bonding process and exposing the substrate by friction on the bonding surface.

In addition, if the oxide layer is completely removed by dry etching, high plasma output or long-time etching is required, resulting in an increase in the temperature of the material. In the sputter etching treatment, when the temperature rises above the recrystallization start temperature of the metal in the high-pressure rolled metal layer, recrystallization of the high-pressure rolled metal layer occurs, and the high-pressure rolled metal layer becomes crystalline or oriented prior to bonding. When the crystal-oriented high-pressure rolled metal layer is rolled, deformation is introduced into the high-pressure rolled metal layer and the biaxial crystal orientation of the high-pressure rolled metal layer is deteriorated. For this reason, in the sputter etching process, it is necessary to maintain the temperature of the high-pressure rolled metal layer below the starting temperature for recrystallization of the metal. For example, when a copper foil is used as a high-pressure rolled metal layer, the temperature of the copper foil is kept below 150°C. It is preferably maintained at 100° C. or lower to maintain the metal structure of the high-pressure rolled metal layer as a rolled aggregate structure.

In addition, even in sputter etching of a non-magnetic metal sheet, if the temperature of the metal sheet is set to a high plasma output or over time, the temperature of the high-pressure rolled metal layer decreases due to contact with the high-pressure rolled metal layer during pressure welding. It rises, and there exists a possibility that recrystallization of a high-pressure rolled metal layer occurs simultaneously with rolling, and the biaxial crystal orientation deteriorates.

For this reason, it is preferable to maintain the temperature of the metal plate below the start temperature of recrystallization of the metal in the high-pressure rolled metal layer even in the sputter etching process of the non-magnetic metal plate. For example, when a copper foil is used as a high-pressure rolled metal layer, the copper foil is kept below 150°C. Preferably, it is good to maintain the high-pressure rolled metal layer at room temperature to 100°C.

After activating the surfaces of the non-magnetic metal plate and the high-pressure rolled metal layer in this way, both are bonded with a rolling roll in a vacuum. The degree of vacuum at this time is preferably high in order to prevent re-adsorption on the surface, but the degree of vacuum in the range of 10 ^-5 Pa to 10 ^-2 Pa may be sufficient.

In addition, since the adhesion strength between the two is lowered due to the re-adsorption of oxygen to the surface of the non-magnetic metal plate or the surface of the high-pressure rolled metal layer, it is also preferable to perform the rolling roll bonding in a non-oxidizing atmosphere, for example, in an inert gas atmosphere such as Ar. .

Pressurization by the rolling roll is performed to secure the adhesion area of the bonding interface and to expose the substrate by peeling off some surface oxide film layers due to friction occurring at the bonding interface at the time of pressing, and it is preferable to apply more than 300 MPa, and in particular, non-magnetic metal plate and high pressure Since all of the soft metal layers are hard materials, pressurization of 600 MPa or more and 1.5 GPa or less is preferable. The pressure may be applied more than that, and it was confirmed that the crystal orientation did not deteriorate after the subsequent heat treatment up to 30% by the reduction ratio, but it is preferably pressed so that the reduction ratio is less than 5%. When a pressure exceeding 30% is applied at a reduction ratio, cracks are generated on the surface of the high-pressure rolled metal layer, and the crystal orientation of the crystal-oriented metal layer after rolling and heat treatment deteriorates.

The c-axis orientation ratio of the laminated body of the non-magnetic metal plate and the high-pressure rolled metal layer laminated by the above surface activation bonding is 99% or more, ΔΦ is 6° or less, and the crystal orientation is from (001)[100] to 6 Heat treatment of the high-pressure rolled metal layer is performed so that the ratio of the area deviating from ° or more is 6% or less per unit area. Heat treatment is performed at, for example, 150°C or higher as described above. The heat treatment time varies depending on the temperature, but for example, 400° C. for 1 to 10 hours, and 700° C. or higher for several seconds to 5 minutes. If the heat treatment temperature is set too high, the high-pressure rolled metal layer is liable to cause secondary recrystallization and crystal orientation is deteriorated. In the later process of forming the intermediate layer or the superconducting layer, when considering that the substrate is placed in a high-temperature atmosphere of 600°C to 900°C, heat treatment at 600°C to 900°C is preferable. More preferably, the crystalline orientation and surface roughness of the crystal oriented metal layer and the protective layer formed thereafter are improved by performing the heat treatment at a high temperature after the heat treatment at a low temperature step by step. Specifically, it is particularly preferable to perform heat treatment at 800 to 900°C after heat treatment at 200 to 400°C.

As described above, the substrate for a superconducting wire of the present invention may include a protective layer formed on the crystal oriented metal layer. By plating a laminate of a biaxially oriented crystalline metal layer and a non-magnetic metal plate obtained by heat treatment of a high-pressure rolled metal layer, a protective layer in which the crystalline orientation of the crystalline oriented metal layer is inherited can be formed on the crystalline oriented metal layer.

The plating treatment can be performed by appropriately adopting conditions in which the plating deformation of the protective layer is small. Here, the plating deformation refers to the degree of deformation (warpage) that occurs in the plated film when plating treatment is performed on a base of a metal plate or the like. For example, in the case of forming a layer made of nickel as a protective layer, it can be carried out using a watt bath or a sulfamic acid bath conventionally known as a plating bath. In particular, the sulfamic acid bath is suitably used because it is easy to reduce the plating deformation of the protective layer. The preferred range of the plating bath composition is as follows, but is not limited thereto.

Wattyoke

Nickel sulfate 200g/l~300g/l

Nickel chloride 30g/l~60g/l

Boric acid 30g/l~40g/l

pH 4~5

Bath temperature 40℃~60℃

Sulfamic acid bath

Nickel sulfamate 200g/l~600g/l

Nickel chloride 0g/l~15g/l

Boric acid 30g/l~40g/l

Appropriate amount of additives

pH 3.5~4.5

Bath temperature 40℃~70℃

The current density in performing the plating treatment is not particularly limited, and is appropriately set in consideration of the balance with the time required for the plating treatment. Specifically, for example, in the case of forming a plating film of 2 μm or more as a protective layer, a low current density increases the time required for the plating process, and the line speed is slow to secure the time, resulting in a decrease in productivity or difficulty in controlling the plating. In some cases, the current density is preferably 10 A/dm 2 or more. In addition, the upper limit of the current density varies depending on the type of plating bath and is not particularly limited. For example, it is preferable to set it to 25 A/dm 2 or less for a watt bath and 35 A/dm 2 or less for a sulfamine acid bath. In general, when the current density exceeds 35 A/dm 2, good crystal orientation may not be obtained due to so-called plating burnout.

The formed protective layer may have micro-pits on its surface depending on plating conditions or the like. In that case, if necessary, after plating, averaging by further heat treatment can be performed to smooth the surface. It is preferable to set the heat treatment temperature at this time to 700 degreeC-1000 degreeC, for example.

In addition, in order to maintain good crystal orientation of the intermediate layer and the superconducting compound layer that are further laminated on the protective layer by epitaxial growth, after bonding the non-magnetic metal plate and the high-pressure rolled metal layer as necessary, the surface roughness of the high-pressure rolled metal layer ( You may perform a process for reducing Ra). Specifically, methods such as reduction with a rolling roll, buff polishing, electrolytic polishing, and electrolytic abrasive polishing can be used, and it is preferable to set the surface roughness (Ra) to, for example, 20 nm or less, preferably 10 nm or less by these methods. Do.

3. Superconducting wire

A superconducting wire may be manufactured by sequentially laminating an intermediate layer and a superconducting layer on the substrate for a superconducting wire as described above according to a conventional method. Specifically, an intermediate layer such as CeO ₂ , YSZ, SrTiO ₃ , MgO, Y ₂ O _3, etc., is epitaxially formed on the outermost layer of the substrate for a superconducting wire using a means such as sputtering, and further, Y123-based, etc. Superconducting wire material by forming a superconducting compound layer by a method such as PLD (Pulse Laser Deposition) method, MOD (Organic Metal Deposition) method, MOCVD (Organic Metal Vapor Deposition) method, etc. Can be obtained. Multiple layers may be sufficient as an intermediate layer. If necessary, a protective film made of Ag, Cu, or the like may be further provided on the superconducting compound layer.

Example

Hereinafter, the present invention will be described in more detail based on Examples and Comparative Examples, but the present invention is not limited to these Examples.

(Example 1)

SUS316L (thickness 100㎛) is used as a non-magnetic metal plate, rolled with a reduction ratio of 96% to 99% as a high-pressure rolled metal layer, and the gloss after rolling measured by a color difference meter (Nippon Denshoku Industries, Ltd. Copper foil (18 µm in thickness) was used. SUS316L and copper foil were subjected to surface activation bonding at room temperature using a surface activation bonding device to form a laminate of SUS316L and copper foil.

In the surface-activated bonding, sputter etching was performed under 0.1 Pa with a plasma output of 200 W and a sputter irradiation time of 20 seconds to the bonding surface, and the adsorbed layer of SUS316L and copper foil was completely removed. Further, the pressing in the rolling roll was 600 MPa.

After making the surface roughness (Ra) of 20 nm or less by polishing the surface of the copper foil side of the laminate, heat treatment in a continuous heat treatment furnace under the condition of holding the laminate at 250°C for 5 minutes and then maintaining the crack at 850°C for 5 minutes. And biaxial crystal orientation of the copper foil. Analysis was performed on the surface of the copper foil after the heat treatment using EBSD, which will be described later, and the ratio of the area in which the crystal orientation deviated from (001)[100] by 6° or more was 4.9%.

Next, nickel plating was performed on the copper foil using the laminate as a cathode to form a nickel layer as a protective layer to obtain a substrate. The composition of the plating bath is as follows. Further, the nickel plating thickness was set to 2.5 µm, the plating bath temperature was set to 60°C, and the plating bath pH was set to pH 4.

(Sulfamic acid bath)

Nickel sulfamate 450 g/l

Nickel chloride 5 g/l

Boric acid 30 g/l

Additive 5ml/l

(Example 2)

As the high-pressure rolled metal layer, it was carried out in the same manner as in Example 1 except that a copper foil having a gloss of 43.2 (18 μm in thickness) rolled at a reduction ratio of 96% to 99% was used. Further, the ratio of the area in which the crystal orientation on the surface of the copper foil after heat treatment before forming the protective layer deviates by 6° or more from (001) [100] was 3.9%.

(Comparative Example 1)

As the high-pressure rolled metal layer, it was carried out in the same manner as in Example 1, except that a copper foil (18 µm thick) having a gloss of 55.4 rolled with a reduction ratio of 96% to 99% was used. Further, the ratio of the area in which the crystal orientation on the surface of the copper foil after heat treatment before forming the protective layer deviates by 6° or more from (001)[100] was 10.9%.

The crystal orientation and crystal orientation of the outermost layer of the substrate obtained in Examples 1 and 2 and Comparative Example 1 were measured.

(1) The ratio of the area whose crystal orientation deviates from (001)[100] by more than 6°

The obtained substrate was analyzed using EBSD (SEM-840 of Nihon Electronics Co., Ltd. and TSL Solutions DigiView Co., Ltd.) and crystal orientation analysis software (EDAX OIM Data Collection and OIM Analysis), and the crystal orientation per 1 mm 2 was (001) [100]. The ratio of the area deviating from 6° or more was calculated. Specifically, in "Crystal Orientation", Orientation was set to (001)[100], and the area ratio in each range was calculated by specifying the range of inclination from that direction.

As an example, the analysis result of the board|substrate of Example 2 is shown in FIG. 1, and the analysis result of the board|substrate of Comparative Example 1 is shown in FIG. In FIGS. 1 and 2, a dark gray or gray area indicates a crystal whose crystal orientation deviates from (001)[100] by 6° or more. The substrate of Example 2 shown in FIG. 1 clearly has a smaller area in which the crystal orientation deviates from (001) [100] by 6° or more compared to the substrate of Comparative Example 1 shown in FIG.

(2) In-plane orientation (ΔΦ)

The obtained board|substrate was obtained by using EBSD and crystal orientation analysis software, and analyzing by the following method using <111>//ND of "Crystal Direction":

1. In the crystal coordinate system, rotate the axis to align <111> with ND[001] of the sample coordinate system.

2. Thereafter, how much the <111> axis of the determination coordinate system of each measurement point is inclined with respect to the ND[001] axis of the sample coordinate system is calculated for each measurement point.

3. Display the slope of each point in an integrated graph, and the vertical axis: slope when the number fraction is 0.5: Alignment is 1/2 of ΔΦ. Therefore, ΔΦ is made twice the obtained value.

(3) c-axis orientation rate

With respect to the obtained substrate, θ/2θ was measured with an X-ray diffraction apparatus (Rigaku RINT2000, Inc.), and the c-axis orientation of the (200) plane was measured. Specifically, it was calculated by c-axis orientation rate (%) = I (200) / Σ I (hkl) x 100 (%).

Table 1 shows the results.

(001) Percentage of area out of [100] (%) (001) Percentage of area that is more than 6° out of [100] (%) c axis
Orientation rate ΔΦ
(°) 6°~8° 8°~10° 10°~12° 12°~15° 15° or more Example 1 4.8 0.4 0 0 0 5.2 More than 99% 4.98 Example 2 3.3 1.7 0.3 0.2 0.1 5.7 More than 99% 5.22 Comparative Example 1 10.9 2.3 0.5 0.1 0 13.8 More than 99% 5.58

The substrates of Examples 1 and 2 and the substrate of Comparative Example 1 have a difference in ΔΦ of about 0.3° to 0.6°, respectively, but the ratio of the area in which the crystal orientation of the outermost layer of the substrate deviates by 6° or more from (001)[100] It can be seen that there is no direct corresponding relationship such as a proportional relationship between the ratio of ΔΦ and the area in which the crystal orientation deviates from (001)[100] by 6° or more because the difference is significantly different by 8% or more. That is, if ΔΦ simply decreases, the ratio of the area in which the crystal orientation deviates from (001)[100] by 6° or more does not decrease, and the ratio between ΔΦ and the deviated area is a separate factor.

(Example 3 and Comparative Example 2)

An intermediate layer (CeO ₂ , YSZ, Y ₂ O ₃ ) was formed on the substrates obtained in Example 1 and Comparative Example 1 by RF magnetron sputtering, and on the intermediate layer by a MOD (organic metal deposition; Metal Organic Deposition) method. A superconducting layer (YBCO) having a thickness of 0.15 μm was formed to obtain a superconducting wire. What was obtained from the substrate of Example 1 was taken as Example 3, and what was obtained from the substrate of Comparative Example 1 was taken as Comparative Example 2. The critical current value (Ic) of the superconducting wires of Example 3 and Comparative Example 2 at a width of 10 mm of the superconducting wire was measured. The critical current value Ic was measured in a magnetic field at a temperature of 77 K, and it was taken as a current value when an electric field of 10 ^-6 V/cm was generated. The results are shown in Table 2.

Ic
(A/cm) Example 3 30 Comparative Example 2 20

For the superconducting wire material of Comparative Example 2 using a substrate having a large percentage of the area (13.8%) in which the crystal orientation of the metal in the outermost layer deviates from (001)[100] by 6° or more, the crystal orientation of the metal in the outermost layer is ( In the superconducting wire material of Example 3 using a substrate having a small ratio of areas deviating from [100] by 6° or more (5.2%), it was recognized that the superconducting properties were improved.

(Example 4 and Comparative Example 3)

On the substrates obtained in Example 2 and Comparative Example 1, intermediate layers (CeO ₂ , YSZ, CeO ₂ ) were formed by RF magnetron sputtering, and 0.7 on the intermediate layers by PLD (Pulse Laser Deposition) method, respectively. A superconducting layer (GdBCO) having a thickness of µm, 1.4 µm, 2.1 µm and 2.8 µm was formed to obtain a superconducting wire. What was obtained from the substrate of Example 2 was taken as Examples 4-1 to 4-4, and what was obtained from the substrate of Comparative Example 1 was taken as Comparative Examples 3-1 to 3-4. Table 3 and Fig. 3 show the results of measuring the critical current value Ic at a width of 10 mm of the superconducting wire of the superconducting wires of Examples 4-1 to 4-4 and Comparative Examples 3-1 to 3-4. In FIG. 3, ○ represents the critical current value Ic of the superconducting wires of Examples 4-1 to 4-4, and □ represents the critical current value Ic of the superconducting wires of Comparative Examples 3-1 to 3-4. Show.

Ic
(A/cm) Superconducting layer thickness
(㎛) Example 4-1 165 0.7 Example 4-2 284 1.4 Example 4-3 330 2.1 Example 4-4 382 2.8 Comparative Example 3-1 128 0.7 Comparative Example 3-2 246 1.4 Comparative Example 3-3 267 2.1 Comparative Example 3-4 277 2.8

From Table 3 and FIG. 3, the superconducting wires of Examples 4-1 to 4-4 and Comparative Examples 3-1 to 3-4 show an improvement in superconducting properties with an increase in the thickness of the superconducting layer, but the metal of the outermost layer For Comparative Examples 3-1 to 3-4 using substrates with a large percentage of the area (13.8%) in which the crystal orientation of (001)[100] deviates from (001)[100], the crystal orientation of the metal of the outermost layer is (001) ) The superconducting wires of Examples 4-1 to 4-4 using a substrate with a small percentage of the area deviating from [100] by 6° or more (5.7%) have improved superconducting properties and high critical current density at any film thickness. It has been shown to have.

(Reference example)

Copper foils of various gloss, rolled with a reduction ratio of 96 to 99%, were subjected to heat treatment at 850°C for 5 minutes in a box-type heat treatment, and the copper foil was biaxially oriented. The ratio of the area in which the in-plane orientation degree (ΔΦ) and the crystal orientation of the copper foil deviated from (001)[100] by 6° or more was measured by the EBSD method. The results are shown in Table 4.

Gloss (001) The percentage of the area that is more than 6° from [100] ΔΦ
(°) c-axis orientation rate
(%) 34.3 3.06 4.59 More than 99% 36.4 4.47 5.07 More than 99% 38.9 3.80 4.77 More than 99% 39.4 2.90 4.82 More than 99% 42.8 5.27 4.56 More than 99% 43.2 4.03 4.60 More than 99% 46.2 6.06 4.99 More than 99% 55.1 8.57 4.95 More than 99% 55.4 10.90 5.61 More than 99%

From Table 4, it was found that the ratio of the area in which the crystal orientation of the copper foil deviates by 6° or more from (001)[100] can be 6% or less by using a copper foil having a gloss of 45 or less. In addition, it can be seen from Table 4 that the ratio of ΔΦ and the area in which the crystal orientation deviates from (001)[100] by 6° or more does not have a direct corresponding relationship such as a proportional relationship. In particular, even though the value of ΔΦ became small, it could be seen that the proportion of the area deviating from 6° or more increased in reverse.

All publications, patents, and patent applications cited in the present specification are incorporated herein by reference as they are.

Claims (9)

The crystal orientation of the metal of the outermost layer is 99% or more in the c-axis orientation rate, the in-plane orientation is 6° or less, and the ratio of the area where the crystal orientation deviates by 6° or more from (001)[100] is 6% per unit area. The substrate for a superconducting wire is less than or equal to 0.3% per unit area, and the ratio of the area whose crystal orientation deviates from (001)[100] by 15° or more is less than 0.3%. The method according to claim 1, wherein the non-magnetic metal plate and the crystal-oriented metal layer stacked on the non-magnetic metal plate are formed, or formed on the non-magnetic metal plate and the crystal-oriented metal layer and the crystal-oriented metal layer stacked on the non-magnetic metal plate to determine the crystal orientation of the crystal-oriented metal layer. A superconducting wire substrate made of an inherited protective layer. The method according to claim 1 or 2,
A substrate for a superconducting wire in which the outermost layer is made of copper, nickel, or an alloy thereof. A method of manufacturing a substrate for a superconducting wire having a crystal-oriented metal layer, wherein a high-pressure rolled metal layer having a rolled texture is heat-treated to perform crystal alignment, so that the c-axis orientation rate is 99% or more, and the in-plane orientation degree ΔΦ is 6° or less, and The ratio of the area whose crystal orientation deviates by more than 6° from (001)[100] is 6% or less per unit area, and the ratio of the area whose crystal orientation deviates from (001)[100] by more than 15° is less than 0.3% per unit area. A method of manufacturing a substrate for a superconducting wire material, comprising a step of forming a crystal-oriented metal layer. The process of laminating the non-magnetic metal plate and the high-pressure rolled metal layer by surface activation bonding, the c-axis orientation rate is 99% or more, the in-plane orientation is 6° or less, and the crystal orientation is 6° or more at (001)[100] Including the process of heat treatment of the high-pressure rolled metal layer so that the ratio of the deviated area is less than 6% per unit area, and the ratio of the area deviated by 15° or more from (001)[100] is less than 0.3% per unit area. A method of manufacturing a substrate for a superconducting wire. The method of claim 5,
A method for producing a substrate for a superconducting wire member having a gloss L value of 45 or less obtained by measuring L*, a*, b* of the high-pressure rolled metal layer before lamination with a color difference meter. The method according to any one of claims 4 to 6,
A method for producing a substrate for a superconducting wire in which the high-pressure rolled metal layer is selected from at least one selected from the group consisting of nickel, copper, silver, and aluminum, or an alloy thereof. The method according to any one of claims 4 to 6,
A method of manufacturing a substrate for a superconducting wire in which a high-pressure rolled metal layer is heat-treated at 200 to 400°C and then heat treated at 800 to 900°C. A superconducting wire having a superconducting wire substrate according to claim 1 or 2, an intermediate layer stacked on the substrate, and a superconducting layer stacked on the intermediate layer.

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